Method of mixing concrete and similar cementitious materials.



H. P. BROWN. NG CONCRETE AND SIMILAR CEMENTITIOUSMATERIALS.

METHOD OF MIXI "APPLICATION FILED nc.24; I914.

' Patented Mar. 11,1919.

WITNESSES v gamma/r01? ATTORNEY HAROLD P. BROWN, OF NEW YORK, N. Y.

Specification of Letters Patent.

Application filed December 24, 1914. Serial No. 878,849.

To all whom it may concern.

Be it known that I, HAROLD P. BROWN, a citizen of the United States, anda resident .of the borough of Manhattan of the city of New York, in theState of New York, have invented certain new and useful Improveinents inMethods of Mixing Concrete and Similar Cementitious Materials, of whichthe following is a specification, reference being had to theaccompanying drawing, forming a part hereof.

This invention, while concerned incidentally with the provision of newapparatus for carrying on the mixing of concrete, is concernedparticularlywith a new and improved method for producing a cementitiousconglomerate, composed generally of water,

' sand, stone and cement, or other suitable material'sfin properproportions, which shall possess all of those properties which aregenerally recognized to be desirable in concrete. One of the greatestdifliculties in placing concrete which shall be strong, hard andwater-proof, is due to the time which usually elapses between thehydration and the set ting, it being well known that the sooner theconcrete sets, the more effective the bond.

During the time of the conveying of the con.

crete from the mixer to the place where it is to be applied, it isevident that the n'uxture must remain as a plastic solid and no portionthereof must be permitted to set.

This plastic condition can be maintained by the presence of an excess ofwater which is undesirable for the reason that hydration is moreeffective when just the right amount of *water is combined with theconstituents of the concrete. Or such plastic condition can bemaintained by continuous mechanical agitation, stirring or other mixing,in a tube leading from the mixer to the Point of application. It is theobject of this invention to improve the character of cement, not byshortening the elapsed time between the mixing and the placing (for thatis obviously impossible) but by making it unnecessary to add anexcessive amount of water to prevent premature setting. In accordancewith the invention, the concrete is mixed in the presence of a hotelastic gaseous element under more or less pressure,which has thepeculiar property of accelerating or assisting hydra tion during themixing and of accelerating drying and crystallization after theconcreteis placed, the hydration being effected with just the right amount ofwater and the premature setting being prevented bythe peculiar action ofthis gaseous element on the mass. In practice, dry superheated steam hasbeen found to be the most inexpensive and eliicient element, although asthis description proceeds it will be evident that heated compressed airor gas will satisfy many of the specified requirements.

The steam at suitable pressure is piped source to assist the hydrationduring the mixing and appears to bring about some physical or chemicalinter-action between the materials which, when hydration is completed,will maintain the plasticity of the mass until it is deposited at thedesired place. The effect of the steam, the heat and the pressure on theconcrete after placing seems to be to dry and crystallize it so that thesetting is completed within a comparatively short time and a. verydense, nonporous and somewhat vitreous monolithic structure isdeveloped.

Furthermore, the said dry superheated steam in addition to increasingthe crystallizing process and maintaining the temperature duringtransit, also opens up the pores of the cement to perfectly hydrate itand opens up the pores oi; the sand and pebbles while Patented Mar. 11,1919.

" into the mixer drum from any available I the pressure forces theperfectly hydrated I cement into these pores and hence produces acoating which adheres firmly to the sand and pebbles, causing them tocompactly unite during the setting period.

Suitable apparatus for practising the imis rotated and the mixturetherein thoroughly agitated. It will be obvious that any other form ofapparatus for mixing theconcrete may be employed.

The trunnions a of the drum a are tubular in the illustrated embodimentand have connected thereto steam pipes f and f which are coupled to asteam supply. pipe 9 leading from. any available source of steam, suchas the boiler h. To secure the be t results, it is desirable to have asuperheater i interposed in the steam line a. drain pipe or separator 76communicating With the line between the superheater and the boiler h.Suitable valves'are indicated generally at f f 9 and k, for controllingthe passage of fluid through the respective portions of the system andan adjustable pressure regulating valve is shown at 9. For

instance, by means of the-valve it becomes v possible to regulate thequantity of steam Icy-passed through the super-heater t. The use of theremaining valves will be evident to one skilled in the art.

In operation, the materials are introduced into the drum n as through atrap a -'a-nd steam is admitted into the drum through the pipeconnections 7', f, or through either one. Where the materials are at a.low temperature, it Will be desirable to pass steam through the drum forshort time before the mixing operation is commenced.

As has been noted before, the presence or steam under pressure duringthe mixing ofthe materials has proved to be very effective in producingconcrete With such properties as are recognized to be desirable.However, the presence of heat in some other "form dun ing this mixingope-ration falls Within the scope of, this invention as the resultsobtained in practice are believed to be due partially to the presence ofheat and pressure and partially to the use of an elastic gaseouselement.

While the apparatus illustrated herein is believed to be new whenconsidered with re spect to the interrelation or" the separate elements,it is obvious that modifications in the structure of each or" theelements and changes in the arrangement and connections be made Withoutdeparting from the ating conditions specified in the appended claims.

Although a variety of types of mixers may be used in'pertormin thismethod, mixers designed to raise the concrete materials and to thenpermit them to fall through the atmosphere of the gaseous medium andthus be completely subjected to the action thereof are round to be mostsuitable. Such mixers are those with blades secured to the interior ofthe rotary drum or those with agitating paddles.

In order to avoid excess'of Water in the concrete,. in case the steam isused as a gaseous medium, it is advisable to have dry "iper-heatedsteam. The super-heater and separator illustrated lend themselvesreadily to the production of'such steamu, in the absence ofsuper-heater, steam of high pressure Wir -drawn to low pressure .throughregulating valve, may also be used.

I claim as my invention:

1. The method of mixing concrete and similar cementitious material whichconsists in applying superheated steam to the ingredients during mixing.

2. The method of mixing concrete and similar cementitious material whichconsists in submitting the ingredients to be mixed to pressure andapplying superheated steam to said ingredients during the mixing opera-'tion.

This specification signed and witnessed this 7th day of December, A. D.1914.

HABULD P. BROVJN.

Signed in the presence oi deems Costner.

Aurrronr Tnoarrson.

